Comparison circles
The drawing of comparison circles is a way to show whether the mean values for various categories (boxes in the box plot) are significantly different from each other. The circles are drawn with their centers at the mean value for the box to which it corresponds.

In the example above, the sum of sales is shown for a number of different fruits and vegetables. The box for Pears has been marked, which is also indicated in the corresponding comparison circle. The marked comparison circle is shown with a darker border and a transparent fill. By looking at the comparison circles or the little relation indicator at the bottom of the visualization area (circled in red on the image), one can see that the sum of sales for Lettuce does not display a significantly different group mean, whereas the group means for all other fruits and vegetables are significantly different from that of Pears. The square in the relation indicator indicates the marked box and the lines in the relation indicator extend to any boxes that are not significantly different from the marked one.

- Comparison circles algorithm
The drawing of comparison circles is a way to show whether or not the group means for all pairs are significantly different from each other. The Tukey-Kramer method is used for the calculation. Each group (each box plot) gets a circle where the center of the circle is aligned with the group mean value.